Effects of phase difference and stress ratio on biaxial tension–tension fatigue crack propagation behavior of rolled ZK60 magnesium alloy

Abstract

The effects of phase difference and stress ratio on in-plane biaxial tension–tension fatigue crack propagation behavior of rolled ZK60 magnesium alloy were explored in this study. The initial crack propagation angle φ was computed and compared via finite element and analytical methods. The biaxial fatigue crack propagation rate and fractographic analysis were also investigated to identify reasonable fracture parameters and crack propagation mechanisms, respectively. Results show that the initial crack propagation angle could be accurately computed by the finite element method. The energy release rate range ΔG considers the effects of modes I (KⅠ) and II (KⅡ) stress intensity factors. Thus, ΔG is a reasonable fracture parameter for describing the fatigue crack growth rates with phase differences. ΔKeff and ΔG could uniformly describe the biaxial fatigue crack growth rate of ZK60 magnesium alloy under different stress ratios. Furthermore, the crack growth mechanism of ZK60 magnesium alloy is identical under different stress ratios and varies under phase difference.